Will These Alzheimer's Drugs In Phase 3 Clinical Trials Cross The Finish Line?

Alzheimer's disease is an irreversible, progressive brain disorder causing problems with memory, thinking and behavior. An estimated 5.7 million Americans are said to have Alzheimer's disease, and this number is projected to exceed 7.1 million by 2025.

According to the Alzheimer's Association, the disease will cost the nation an estimated $277 billion, including $186 billion in Medicare and Medicaid payments. This projected cost is nearly $20 billion higher than last year, and by 2050, the costs are expected to be in excess of $1 trillion.

Alzheimer's is the 6th leading cause of death in the U.S., and there is no cure yet for this neurodegenerative disease. The available medications for Alzheimer's can only alleviate symptoms temporarily, and they don't work for everyone.

The FDA-approved medications to treat the symptoms of Alzheimer's disease include:

-- Donepezil, marketed under the brand name Aricept, to treat all stages of the disease-- Galantamine, marketed under the brand name Razadyne, for mild-to-moderate stages-- Memantine, marketed under the brand name Namenda, and Memantine/Donepezil combo drug, marketed under the brand name Namzaric, to treat moderate to severe stages and -- Rivastigmine, marketed under the brand name Exelon, for all stages of Alzheimer's.

No new Alzheimer's drug has been approved since 2003 - the year, in which Forest Labs' Namenda was approved in the U.S.

The development of Alzheimer's drugs has been marred by a high failure rate. A U.S. study, which analyzed how the Alzheimer's clinical trials fared during the period of 2002 to 2012, revealed a failure rate of 99.6% compared to a failure rate of 81% for cancer drugs.

So far this year, 5 drugs have failed in clinical testing - 4 in late-stage and 1 in mid-stage trials.

The Alzheimer's drug candidates that flopped in phase III testing this year are Takeda's Pioglitazone in January; Merck's Verubecestat in February; vTv Therapeutic's Azeliragon in April and Eli Lilly/ AstraZeneca PLC's Lanabecestat in June. Johnson & Johnson halted its mid-stage trial of Atabecestat in Alzheimer's patients in May, following safety issues.

The high-profile disappointments only go on to prove that Alzheimer's drug development is still a quagmire for pharma companies. It is here that some interesting questions arise.

-- Have researchers fully understood the complex nature of this nefarious disease?-- Do Aß (amyloid ß-peptide) and tau proteins provide the appropriate targets for AD therapies? Amyloid-ß (Aß) and phosphorylated tau tangles are considered to be major pathological hallmarks of Alzheimer's.

Well, if we have the answers for the above two questions, we can know how close or how far are we in finding a cure for Alzheimer's.

Despite the high failure rate, the pharma companies have not shied away from making investments in Alzheimer's research.